Thermostat



J. F. HOR SHAM. THERMOSTAT. APPL lCATlON FILED OCT 1?. I918- 1 118,928 I PatentedJune 6, 1922.

' //v VEA/TOR sa /aw,

UNITED STATES PATENT OFFICE.

JOHN mmimmox HORSHAM, OF'LAUR-EL HILL, new Yonx. I

' mrmmosra'r.

To all whom it may concern:

Be it known that JOHN FREDERIUK.HORS- HAM, citizen of United States, residing at Laurel Hill, Queens County, New York, has

invented a new and useful Improvement in Thermostats, of which the following is a specification.

t This invention relates to thermostats and it has for an object to provide a cheap and inexpensive thermostat which is characterthey may be used for ther purposes as well,

as will beun erstood. M

The invention has for a further object to provide a simple arrangement for the testing of the operative condition of'the thermostat and circuit, whether the thermostat is employed singly or as one of a string.

For further comprehension of the invention, and of the objectsv and advantages thereof, reference will be had to the following description and accompanying drawings,

and to the appended claims in which the various novel features of the invention are more particularly set forth.

Figure 1 of the drawings is a vertical sectional view of a thermostat constructed according to my invention.

Figure 2 is a horizontal section on the line 22 of Figure 1.

Figure 3 is a horizontal section on the line 3-3 of Figure 1;

Figure 4'i's a diagram ofthe electric circuit employed when a single; thermostat is employed with thealarm.

As here shown, my improvedthermostat 4. com rises a tube 1 the lower end of which 'is c osed, andenlarged as at 2, to form a receptacle for a contact-bridging liquid 3,

preferably mercury. I

Extending downwardly within this tube from a point about midway of its height is a second, smaller tube v5 which is open at top and bottom and has. its lower end pro- -jecting into the mercury 3. The annular space between the top of this tube 5 and the main tube 1' is sealed as shown at 6. The

tube 1 is also preferably formed near its upper end with an enlargement 7 to provide an air chamber. These tubes 1 and 5 may be made of any suitable material. In the embodiment of the invention here shown they are formed of glass.

. normally open hand switch 21.

leads through a battery 22 to the other tar-- specification of Letters Patent. Patented June 6, 1922. Application filed October 17, 1918. Serial No. 258,664;

r The portion of the outer tube which extends above the inner tube is enclosed in a jacket 8. of heat-insulating material, such as asbestos to prevent the heated air coming directl in contact with the tube. The lower portlon of the tube may be protected from damage, when formed of glass, by any suitable. means such as the skeleton metallic structure 9; A plug 10 of any suitable material such as porcelain or plaster of Paris closes the upper end of .;the tube 1.

Extending downwardly through a central aperture in the plug 10, and into the tube 5, are a seriesof insulated Wires 15, 16, and 17 the tips ofwhich are bared. The wires 15 and 16 extend into the mercury 3 while the Wire 17 terminates at a distance above the mercury.

In use the wires 15, 16, and 17. are connected to a suitable alarm indicator in a manner to cause an alarm to be given when minal of the bell 20, while a wire 23 connects the battery 22 with the other terminal of the hand switch 21. i

It will be apparent, of course, that any desired number and character of alarm devices maybe employed in lieu of, or supplementary to, the bell 20.

.The operation-of the thermostat as constructed according to my invention is as follows:

I The lower portion of the tube 1 constitutes a closed air chamber-as will be apparent. When the temperature in the vicinity of the thermostat rises this air is caused to expand. The air in the upper portion of the tube, which is protected by the heat-insulating jacket 8, remains cool and in consequence the increased pressure in the lower chamber acts on the mercury and forces it upward in the inner tube 5.11ntil it touches the wire 17. A circuit is thus closed through the mercury, wire 17 battery 22, bell 20, and wire 15, causing the alarm to sound.

If at any time it is desired to test the alarm Wire 17 system, switch 21 is closed completing a circuit through wire 23 battery22 bell 20, wire 15 and the mercury in the thermostat.

It will be apparent that I have provided a thermostat characterized by great sensitiveness to temperature changes and by rapidity of action as the expansion of the air in the lowerchamber in the thermostat will result in a high ratio of movement of the mercury in the tube 5 by reason of the small area of such tube in comparison with the total area of contact between the air and mercury.

WVhat I claim as my invention and desire to protect by Letters Patent is as follows:

1. In a thermostat, a pair of separated air chambers each of which is closed to the outer air, a contact-bridging liquid in one of said chambers, a conduit leading from the lower portion of the other one of said chambers into the first mentioned chamber and having one end extending downwardly into the said liquid, electrical contact members one of which is located in the said conduit above the normal level of the said liquid and a heat-insulating jacketenclosing the chamber-from which said conduit leads.

2. A thermostat comprising" a substantially cylindrical receptacle having an enlarged bulb at its lower end and a second enlargement near its upper end, a contactsurrounding the receptacle above the said sealing means.

3. A thermostat comprising a substantially cylindrical receptacle having an enlarged bulb at its lower end and a second enlargement near its bridging liquid in the said bulbfa tube open at both ends extending downwardly in the said receptacle from a point below the said second enlargement into the said liquid, means sealing the space between'the upper end of said tube and the wall of the receptacle, a pair of electrical contact members in normal contact with the'said liquid, and a heat-insulating jacket surrounding the receptacle above the said sealing means.

In testimony whereof, JOHN FREDERICK ORSHAM has signed his name to this specition this 4th day of May, 1918. i

JOHN FREDERICK HORSHAM.

upper end, a contact-- 

